Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/5/2004
Publication Date: 5/1/2004
Citation: Ynturi, P., Jenkins, J.N., McCarty Jr, J.C., Saha, S. 2004. Segregation for root-knot nematode resistance gene(s)in F2 populations from resistant x susceptible crosses [abstract]. National Cotton Council Beltwide Cotton Conference. p. 1112.
Technical Abstract: One of the serious pests of upland cotton (Gossypium hirsutum L.) is the southern root-knot nematode (RKN), Meloidogyne incognita (Kofoid and White) chitwood race 3 that causes severe yield losses to cotton. This study was conducted to identify mode of genetic inheritance of RKN resistance genes using two F2 populations derived from two different crosses (Resistant Near Isogenic Line X Susceptible Near Isogenic Line) and (Resistant Near Isogenic Line X ST213). The segregation of resistant and susceptible genes in these two F2 populations was determined using gall index ratios. All the plants were evaluated in a greenhouse experiment for root galling index after being grown for six weeks in pots inoculated with nematode eggs. Root galling was rated using an indexed scoring system ranging from 1 (least galling) to 5 (severe galling). First, out of one hundred and twelve F2 progenies obtained from a cross of (RNIL X SNIL), thirty-two scored resistant and eighty scored susceptible. Out of one-hundred and ten F2 progenies obtained from a cross of (RNIL X ST 213) twenty-nine scored resistant and eighty-one scored susceptible. The probability (p) values for the ratios (3:1) and (13:3) in both populations are greater than 0.05. These results indicated an approximate segregation ratio of 3:1 or 13:3 for susceptible and resistant in both F2 populations, suggesting a single recessive gene or one dominant and one recessive gene may be involved in controlling the resistance trait. Further F2 populations are being screened using SSR primers.